Vacuum-type circuit breaker with connection terminals

ABSTRACT

A vacuum contactor has one connection terminal for the upper and lower end of each vacuum interrupter. At least the upper connection terminal has a metal member that is dimensioned essentially as a function of a current to be carried. A separate holder of insulating material is used to join the metal member to wall parts of an insulator body that accommodates the vacuum interrupters. In this manner, the distance between live parts and grounded parts of the vacuum contactor is increased and the reliability with respect to protecting against partial discharges and breakdowns is improved.

BACKGROUND OF THE INVENTION

The invention relates to a vacuum contactor. More particularly, theinvention relates to a vacuum contactor having at least one vacuuminterrupter and a chamber open on one side for accommodating theinsulator body which contains the vacuum interrupter, an upper and alower connection terminal arranged on the insulator body as a connectionbetween the vacuum interrupter and an external electric circuit, each ofthese connection terminals being secured to opposite wall parts of theinsulator body, and having a connector contact face for an externalconductor.

A vacuum contactor of this type is shown in the German companypublication by Siemens entitled Vakuumhochspannungsschutze 3TL6(High-Voltage Vacuum Contactors 3TL6), edition 1988, order No.E86010-K1802-A201-A1. It discloses connection terminals made of metalstructural parts, which are used for both the current transfer and asmeans for mounting on the insulator body. An object of the presentinvention is to improve reliability in the protection against partialdischarges and breakdowns in the area of the connection terminals.

SUMMARY OF THE INVENTION

This objective is solved in accordance with the invention in that theconnector contact face of at least the upper connection terminal is acomponent of a metal member that is dimensioned essentially only as afunction of a current to be carried and a holder made of insulatingmaterial to be joined to the wall parts of the insulator body is used tosecure the metal member. In this manner, the high-voltage potential iskept further away from the grounded components than had been possibleusing existing structural parts of metal. Because of the increaseddistance, the electric field strength is reduced at critical points, sothat the reliability with respect to protecting against breakdowns orpartial discharges is improved. Although it is possible in principle todesign both the upper as well as the lower connection terminal in theindicated manner, it is typically sufficient to only alter the upperconnection terminal accordingly. Because of its increased dielectricstrength, the vacuum contactor can be used in the case of unaltereddimensions for higher nominal voltages than had previously beenpossible.

The invention advantageously makes it possible for the partial area ofthe connection terminals used for current conduction to be simpler indesign than in known methods. In particular, the metal member can have arectangular cross-section and, the holder has a recess adapted to thecross-sectional shape of the metal member. Thus, the recess assumes thefunction of mutually aligning the metal member and the holder. Forexample, the metal member can be a mounting channel that is straight orright-angled at the end, or a cast part of copper with suitable surfaceprotection.

The holder can have projections that protrude in the direction of thenarrow sides of the metal member. In this case, the projections takeover the task of aligning the metal member, while the remaining boundarysurfaces of the recess of the holder can have a certain angle ofinclination to facilitate manufacturing.

In addition, it is recommended that the holder have a stop face todelimit the recess in its longitudinal direction, as well as a cut-awayopening for a fastening element that joins the metal member and theholder. Therefore, when joining together the metal member and theholder, both parts are positioned to align the cut-away opening of theholder with a corresponding cut-away opening in the metal member. Thismakes it possible for a clamping screw to be inserted to join togetherthe metal member, the holder and a flexible conductor that is providedas a movable connection between the connection terminal and the movableterminal stud of the vacuum interrupter.

As with the connection terminals which are made entirely of metal, theholder which is made of insulating material for the upper connectionterminal can have a fork-like design and can have two lateral sides tobe joined to the opposite wall parts of the insulator body. A suitableclearance is provided between the two lateral sides of the upperconnection terminal to allow passage of the movable terminal stud of thevacuum interrupter.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a partial cross section of the vacuum contactor of the presentinvention.

FIGS. 2 and 3 depict a support of a connection terminal in a front view,and a view of the bottom side respectively.

FIG. 4 shows a top view of a metal member having a connector contactface.

DETAILED DESCRIPTION

The vacuum contactor 1 of FIG. 1 comprises a drive assembly box 2 with asolenoid coil 3 for switching on and off a vacuum interrupter 4 which islocated in a chamber 5 of an insulator body 6. The drive assembly box 2and the insulator body 6 are securely joined to one another.

In the case of a multipole design, the insulator body 6 contains anumber of chambers 5 that corresponds to the number of vacuuminterrupters 4.

At its lower end in the area of its fixed terminal stud 7, the vacuuminterrupter 4 is rigidly joined to a lower connection terminal 8, whichhas a metal member 10 and is secured by screws 11 to wall parts 12 ofthe insulator body 6. In the sectional view of FIG. 1, only one of theopposite wall parts 12 is visible. At its end facing opposite theconnection terminal 8, the vacuum interrupter 4 is coupled via itsmovable terminal stud 13 to a rocker-type operating lever 14, whichbears an armature that interacts with the solenoid coil 3. In theillustrated open-circuit condition, the vacuum interrupter 4 is heldagainst the external air pressure acting on it by a tripping spring 15,which is likewise situated in the drive assembly box 2.

An upper connection terminal 16 likewise has a metal member 17 with aconnector contact face 20. In addition, a holder 21 is provided, towhich the metal member 17 is secured. Details with respect to theseparts are given below with the description of FIGS. 2, 3 and 4. FIGS. 2and 3 depict a front view and a bottom view, respectively of the holder21. As these Figures show, the holder 21 which is made of an insulatingmaterial has a recess 22, which corresponds with a certain oversizetolerance to the width of the metal member 17. The wall surfaces 23 ofthe recess 22 are formed as chamfered and rounded off surfaces so as toallow the holder 21 to be advantageously manufactured as a plasticmolded part. Projections 24 protruding in the direction of the narrowsides of the metal member are provided to align the metal member 17 inthe recess 22. In addition, the recess 22 is delimited in thelongitudinal direction by a stop face 25. A cut-away opening 26 (FIG. 4)provided in the metal member 20 and a corresponding cut-away opening 27in the holder 21 thus come into alignment when the metal member 17 isinserted in the recess 22 up to the limit stop on the stop face 25. Theparts then assume the position as is shown in FIG. 1.

As shown in FIG. 3, the holder 21 has a more or less fork-shaped designwith two lateral sides 28 and 30, each comprising two pass-throughopenings 31 for fixing screws. The holder 21 abuts with lateral sides 28and 30 on wall parts 32 in the upper area of the insulator body 6, onlythe lateral side 30 of the holder 21 being visible in FIG. 1. Screws 11are used to secure the holder 21 to the wall parts 32. An assembly screw33 joins together the metal member 17, the holder 21 and a flexiblecurrent conductor 34. The other end of the flexible current conductor 34is connected to the movable terminal stud 13 of the vacuum interrupter4.

The construction of the metal member 17 is advantageously simple andeasy, as it is essentially designed for its task as a current-conductingconnection member. The metal member 17 is designed as an angular castpiece of copper with suitable surface protection. Also, the holder 21 isan insulating mounting part, which can likewise be manufacturedeconomically, for example, as a plastic injection molded part. Incomparison to a connection terminal made only of metal, the high-voltagepotential at the upper end of the vacuum interrupter 4 is not carried asfar in the direction of the metal, grounded drive assembly box 2. Thedielectric loading of the insulator body 6 in this region is, therefore,reduced in comparison to this known design.

Analogously, the lower connection terminal 8 can be made of a metalmember used for current conduction and an insulating holder, the recessof the holder having the above described features. A holder of this typedoes not need fork-shaped lateral sides, because the fixed terminal stud7 fits on the metal member and, therefore, does not pass through theholder. In FIG. 3, a dot-dash line indicates that the right part of thedepicted holder can be used as a holder 35 for the lower connectionterminal 8. Openings 36 drawn with a dot-dash line are provided for thelower fixing screws 11.

We claim:
 1. A vacuum contactor comprising:at least one vacuuminterrupter; a chamber being open on a first side, such that said vacuuminterrupter is contained in an insulator body located in the first sideof said chamber; an upper connection terminal including a metal member;a lower connection terminal; each one of said upper and lower connectionterminals being secured to wall parts of said insulator body, the wallparts being arranged on opposite sides of the vacuum interrupter, eachone of said upper and lower connection terminals having a correspondingconnector contact face for coupling to an external conductor such thateach one of said upper and lower connection terminals is coupled betweensaid vacuum interrupter and an external electric circuit, the connectorcontact face of at least the upper connection terminal being dimensionedas a function of a current to be carried in said vacuum contactor; and aholder made of an insulating material for attaching to at least one ofthe wall parts of said insulator body, said holder securing said metalmember in said insulator body.
 2. The vacuum contactor of claim 1wherein said metal member has a rectangular cross-section and saidholder has a recess having a cross-sectional shape substantially similarto the rectangular cross-section of the metal member.
 3. The vacuumcontactor of claim 2 wherein said metal member has narrow side surfacesand said holder includes projections protruding into the recess towardthe narrow side surfaces of said metal member.
 4. The vacuum contactorof claim 2 wherein said holder includes a stop face, said stop facedelimiting a longitudinal extent of the recess, said holder alsoincluding a cut-away opening, such that a fastening element is insertedinto said cut-away opening to join said metal member and said holder. 5.The vacuum contactor of claim 3 wherein said holder includes a stopface, said stop face delimiting a longitudinal extent of the recess in,said holder also including a cut-away opening, such that a fasteningelement is inserted into said cut-away opening to join said metal memberand said holder.
 6. The vacuum contactor of claim 1 wherein said holderhas a fork-like design including two lateral sides which are joined tosaid opposite wall parts of the insulator body, such that a clearanceexists between said lateral sides to allow passage a movable terminalstud of said vacuum interrupter.
 7. The vacuum contactor of claim 2wherein said holder has a fork-like design including two lateral sideswhich are joined to said opposite wall parts of the insulator body, suchthat a clearance exists between said lateral sides to allow passage amovable terminal stud of said vacuum interrupter.
 8. The vacuumcontactor of claim 3 wherein said holder has a fork-like designincluding two lateral sides which are joined to said opposite wall partsof the insulator body, such that a clearance exists between said lateralsides to allow passage a movable terminal stud of said vacuuminterrupter.
 9. The vacuum contactor of claim 4 wherein said holder hasa fork-like design including two lateral sides which are joined to saidopposite wall parts of the insulator body, such that a clearance existsbetween said lateral sides to allow passage a movable terminal stud ofsaid vacuum interrupter.
 10. The vacuum contactor of claim 5 whereinsaid holder has a fork-like design including two lateral sides which arejoined to said opposite wall parts of the insulator body, such that aclearance exists between said lateral sides to allow passage a movableterminal stud of said vacuum interrupter.